Personal computers are becoming more and more commonplace in today's society. Personal computers typically include a central processing unit (CPU) that is controlled by basic instructions referred to as the operating system of the computer. Generally, the personal computer requires one or more peripheral devices to extend its capabilities. Typical peripheral devices include keyboards, display screens, printers, disc drives, modems, etc. Typically, a device driver is required to interface the operating system of the personal computer with the peripheral devices.
Device drivers are small computer programs that receive instructions and data from the operating system that are independent of the peripheral device for which the instructions and data are intended. The device driver responds to the device independent instructions and data from the operating system to provide instructions and data to the peripheral device that are dependent upon the nature and construction of the particular peripheral device. Accordingly, device drivers will typically provide additional information to the peripheral device to enable the peripheral device to perform the functions requested by the operating system. By providing different device drivers with different peripheral devices, the operating system of the computer can interface with peripheral devices made from different manufacturers.
So that the personal computer can interface with all of its peripheral devices, the device drivers must be loaded into the computer memory and initialized prior to operation of the personal computer. Typically, loading the device drivers usually occurs when the personal computer is turned on. When the personal computer is turned on, the operating system performs functions necessary prior to operation. As mentioned above, one of these functions is to load the device drivers from a permanent storage location into the computer memory.
Presently, two methods exist for loading and initializing device drivers into the computer memory when the computer is turned on. The first method relies upon configuration data, a file typically called CONFIG.SYS., being stored in the computer's memory to determine which device drivers are stored in permanent memory and to load and initialize these device drivers. When a new device, and device driver, are added to the personal computer, the CONFIG.SYS file is updated to include information identifying the new driver, its location on the disk, and the location of its initialization program. Accordingly, when the CONFIG.SYS file is accessed, it includes all necessary information to locate each device driver and the routine for loading and initializing the device driver. The operating system uses the CONFIG.SYS file to execute these routines so that each device driver is loaded and initialized.
The other presently available method for loading and initializing device drivers is referred to as ROMDOS. The ROMDOS method enables the device drivers to be stored in read only memory (ROM). To load the device drivers, however, the ROMDOS method relies on the CONFIG.SYS file. Accordingly, the ROMDOS method must provide instructions and data to simulate a hard disk so that the device drivers stored in read only memory (ROM) can be accessed using the CONFIG.SYS file. Further, the ROMDOS method relies upon a subprogram, typically referred to as CONFPROC.SYS, to interface with the CONFIG.SYS file thereby enabling the CONFIG.SYS file to identify and load the device driver stored in read only memory. Although effective, this method requires unnecessary memory for storing the CONFPROC.SYS subprogram. Further, this method creates additional inefficiencies in operating the computer and in storing the device drivers.
Accordingly, it is desirable to provide a method for storing device drivers in read only memory so that the device drivers can be loaded with minimum storage overhead and without changing the underlying device drivers.